The invention relates to a manpower-driven cycle comprising:
a frame with a straight bar equipped with a front steering wheel and a rear drive wheel,
actuating means with a gripping handle operated by the user in a back-and-forth rowing movement,
a driving mechanism transforming said back-and-forth movement into a rotation movement of the rear wheel,
and means for guiding the front steering wheel in rotation.
Manpower-driven cycles transforming a rowing movement exerted by the user into a motion identical to that of a conventional bicycle are well known in the art. These cycles are intended for rowers who wish to discover new training grounds or for cyclists who want to have a complete muscular training. The benefits of rowing can thus be combined with the pleasures of cycling.
Such cycles are described in the documents DE 196 14 836 and EP 0 197 569. The transmission mechanisms used for directional steering and to transform the back-and-forth movement into a rotation movement of the wheel require complicated kinematics.
The object of the invention is to achieve a cycle with a rowing mechanism that is easy to implement and has good stability when negotiating bends.
The device according to the invention is characterized in that the driving mechanism comprises:
a steering and maintaining device formed by a telescopic actuating system with tubes articulated in parallelograms deformable in the longitudinal direction of the bar,
and axial centering means to maintain the axis of the handle constantly in the vertical mid-plane passing through the bar.
According to one feature of the invention, the axial centering means comprise at least one pair of toothed sprockets or sectors linked by connecting rods to the telescopic actuating system.
The user, sitting on the seat with his feet on the foot-rests and his hands on the handle, performs a rowing movement. The presence of the telescopic actuating system prevents any lateral movement of the handle, the axis of the latter remaining constantly in the vertical mid-plane passing through the central bar of the frame.
According to a preferred embodiment, the driving mechanism comprises a transmission device equipped with a traction cable having one end securedly affixed to the handle with back-and-forth movement and an opposite end linked to the drive chain of the rear wheel freewheel. The traction cable passes via at least one counter-pulley and through the hollow interior of the central bar. The means for guiding the front steering wheel in rotation comprise a steering cable linked to a driving pulley securedly affixed to the handle and to an operating pulley coupled to the rotating front fork of the steering wheel. The intermediate part of the steering cable zigzags on pulleys provided along the opposite edges of the parallelograms of the telescopic actuating system and on at least one counter-pulley located at the front of the cycle.
According to another feature of the invention, the steering and maintaining device is fitted with limited pivoting around a transverse axis between an appreciably horizontal lowered position and a raised position.